Implantable medical devices (IMDs) such as pacemakers and implantable cardioverter defibrillators are utilized in monitoring and regulating various conditions within the body. An implantable cardioverter defibrillator, for example, may be utilized in cardiac rhythm management applications to monitor the rate and rhythm of the heart and for delivering various therapies such as cardiac pacing, cardiac defibrillation, and/or cardiac therapy. In some cases, for example, the implantable medical device can be configured to sense various physiological parameters occurring in the atria and/or ventricles of the heart or at other locations to determine the occurrence of any abnormalities in the operation of the heart. Based on these sensed parameters, the medical device may then deliver an appropriate therapy to the patient.
A variety of techniques have been developed for transmitting wireless signals between medical devices located inside or outside of the body. In an ultrasonic approach, for example, each linked medical device can be equipped with an ultrasonic transducer adapted to generate an acoustic signal for providing data communications from one device to another device, to transfer energy from one device to another device, and/or to delivery therapy to a treatment site. One major obstacle limiting the advancement of the ultrasonic approach is the inefficiency of signal transfer from indirect acoustic pathways within the body between ultrasound-enabled devices. In a dynamic, heterogeneous environment such as the human body, for example, optimal signal transfer from one ultrasound-enabled device to another requires appropriately designed transmissions, typically in the form of modulated acoustic signals with compensations for phase and amplitude effects during propagation. Accordingly, there is an ongoing need for systems and methods for improving the accuracy, efficiency, and reliability of wireless signal transfers between ultrasound-enabled devices.